Women have been bleaching their hair for thousands of years. Some of the primitive concoctions used to bleach hair in early Rome, prior to the beginning of the Christian era, included native minerals such as alum, soda, and wood ash combined with wine dregs or water. Such preparations were often left on the hair for several days, and lightened very dark hair to a desirable reddish gold in color. A number of books published during the Renaissance also disclose various formulas for bleaching hair. Typically these compositions were based upon ingredients such as alum, borax, or soda, in combination with plant extracts. It has also been reported that Venetian women obtained their blond hair by sponging it with a solution of soda (or rock alum, black sulfur, and honey) through the hair, spread it over the broad brim of a crownless hat, and let it dry in the sunlight [Cosmetics: Science and Technology, Second Edition, Volume 2, 1972]. This treatment persisted for hundreds of years thereafter, until the fashions changed.
Modern hair bleaches are much milder and non-toxic when compared to their historical counterparts. The key ingredient is a mild oxidizing agent, which is most often hydrogen peroxide. Hydrogen peroxide exerts both a chemical and physical effect on the hair. It is capable of penetrating the hair cuticle and oxidizing the melanin (which provides color) so that the hair becomes noticeably lighter. If treated for a long enough period of time, hair can be colored to very light blonde or white, although it has been said that hair bleached with hydrogen peroxide only may tend to exhibit a yellowish tinge.
Currently, hair bleaches are most commonly found in the two component kit form. One component comprises an aqueous based hydrogen peroxide containing solution or emulsion. The second component comprises a powdered bleach composition that contains persulfate salts which act as accelerators of the bleaching process when the two components are combined. The hydrogen peroxide and persulfates are very reactive when combined and form nascent oxygen in addition to hydrogen and sodium sulfide. The nascent oxygen greatly facilitates oxidizing and bleaching of melanin from the hair. Typical bleaches generally have a pH of 9 to 11 and are applied to hair for 30 to 60 minutes to achieve the desired results.
While modern bleaches are significantly improved when compared to their pre-historic counterparts, there are still many need gaps in the standard bleaching process. One chronic consumer complaint is that the bleaching process takes too long. The 30 to 60 minutes required is simply too inconvenient for modern time-pressed consumers. In addition, the high pH and oxidizing agents may cause damage to those who have overly sensitive hair, particularly with repeat procedures. Accordingly, the gold standard for hair bleach is to provide bleach compositions that work in as short a time period as possible without damaging the hair, and at the same time achieving optimal lightening of hair.
It has been discovered that if the bleach composition applied to the hair has certain specific properties, the amount of time required to bleach the hair can be significantly reduced and the resulting composition is much “kinder” to the hair, even providing a conditioning effect.
Three parameters have been defined as contributing to a shorted time period to achieve hair bleaching. The first parameter is the active oxygen concentration in the bleach composition. As previously noted, it is nascent, or active, oxygen that causes bleaching of the melanin in the hair fiber. If the bleach composition does not contain an adequate level of active oxygen, the bleach will not adequately lighten hair. The second parameter is total alkalinity concentration. It has been found that the proper concentration of alkaline ingredients promotes opening of the hair cuticle and facilitates penetration of active oxygen into the hair fiber. Compositions that do not exhibit sufficient alkalinity are not as effective in lightening hair because the hair cuticle is not as penetrable. However, the amount of total alkalinity cannot be too high otherwise the composition can potentially cause irritation to skin and scalp. The third parameter that has an impact on optimal bleaching of the hair is the presence of a hydrophobic oil in the bleach composition. It has been discovered that the hydrophobic oil promotes more effective penetration of the active components into the hair shaft. Without being bound by this explanation, it is believed that the hydrophilic, water soluble bleach active ingredients are preferentially absorbed into the hair shaft because of their insolubility and incompatibility with the hydrophobic oil which “pushes” the water soluble ingredients away and into the hair shaft. The hydrophobic oil then deposits on the hair fibers and exerts a conditioning effect.
It is an object of the invention to provide a bleach composition that bleaches the hair in a reduced amount of time, prepared by combining an aqueous oxidizing agent composition, a persulfate composition, and optionally, an oil composition.
It is a further object of the invention to provide a bleach composition that contains a hydrophobic oil in an amount sufficient to cause preferential penetration of active ingredients into the hair shaft.
It is a further object of the invention to provide a bleach composition that also conditions the hair.